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arXiv:2503.03411 · Physical Review Applied

Deterministic generation of multiqubit entangled states among distant parties using indefinite causal order

Wen‐Qiang Liu, Hai‐Rui Wei

Published May 27, 2025• 10 citations
arXivHTMLPDF

Abstract

Quantum entanglement plays an irreplaceable role in various remote quantum information processing tasks. Here we present protocols for generating deterministic and heralded $N$-qubit entangled states across multiple network nodes. By utilizing a pre-shared maximally entangled state and single-qubit operations within an indefinite causal order framework, the multi-qubit entangled state between distant parties can be generated deterministically. The complex entangled state measurements and multiple pre-shared entangled states, are essential in conventional entanglement swapping technique, but are not required in our approach. This greatly reduces the complexity of the quantum circuit and makes it more experimentally feasible. Furthermore, we develop optical architectures to implement these protocols by encoding qubits in polarization degree of freedom. The results indicate that our protocols significantly improve the efficiency of long-distance entanglement generation and provide a practical framework for establishing large-scale quantum networks.

DOI
10.1103/physrevapplied.23.054075

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Abstract In this paper, we propose a perfect entanglement swapping protocol for generating a shared three-qubit W state between two remote parties in a deterministic manner. Our method offers a reliable alternative to existing probabilistic protocols for W state entanglement swapping, which is crucial for various quantum information processing tasks. We present a detailed quantum circuit design, implemented using the Qiskit simulator, that outlines the preparation of W states and the execution of joint measurements required for the entanglement swapping process. Furthermore, we analyze the effects of imperfect operations and noisy communication channels on the fidelity of the resulting shared W state. To address these challenges, we introduce a weak measurement-based purification method that enhances fidelity in the presence of amplitude damping. Through mathematical analysis and Qiskit simulations, we demonstrate the effectiveness of our proposed protocol, offering a practical solution for high-fidelity W state generation in real-world quantum communication scenarios.